1. Field of the Invention
The present invention relates generally to resistance welding. More particularly, the present invention is directed to generating spot weld schedules to be implemented by weld controllers.
2. Description of the Related Art
Automobile body panels are spot-welded using a welding apparatus including a robot and a spot welding servo gun coupled to a wrist portion of the robot. The spot welding servo gun has a pair of electrode tips for pressing a work piece therebetween. The electrode tips are electrically connected to a welding transformer. The welding transformer is electrically connected to a welding power source via a controller having a timer function. At least one tip of the spot welding servo gun is movably installed in a servo motor which performs position control or pressure control of the electrode tip.
Many spot welds experience expulsion. That is, molten metal is ejected from the weld decreasing the cleanliness of the mass produced automobile body and compromising the weld integrity. There are five primary causes of expulsion: (i) gun alignment, (ii) condition of the tip of the electrodes, (iii) weld schedule, (iv) misfit parts, and (v) adhesives between the parts.